Lens



Oct. 20, 1925. 1,557,563

Filed July 12 i922 clearly distinguish objects ahead without, howeven pr'oducing "the'blinding glare which "is an annoying-feature of the headlights now surfacesm'entioned lnay be'madetranslucent in common nse, particill arly'if the'headlight 1 lamps are out'offocns, Inaddition, myim- 3' proved lens casts a snBst'an'tiaP amount of lightlat'erally and rearwardly so as to widen and rearwardly.

Patented Oct. 20, 1925.

NET OFFICE.

Jon-N *DAHLSTROZM, or 'rrrrsnnaen, PENNSYLVANIA.

To all whom it wiayconcrn:

"Be it known thatIQJO'HN D'AHLsTRoM, a

citizen, of the Un'ited"States, and "resident of clear, and exact description thereof.

My invention relatesto lenses for use" in vehicle headlights and forgeneral indoor or outdoor illuminating purposes.

The object of my in"v'entionis to provide a lens which shall cast sufficient light in the directionlof its central axis withoutjproduc- 111g a bhndlng glare andwhlch, in addition,

shall direct a portion of the light-laterally 'As' applied to vehicle headlights, my invention aims tolproduce" a lens whichshall cast in front of the vehicle a beamfl'of light s'uliiciently strong to'enable 'the 'driver to the driversvisionbf :the roadway.

' In the accompanying drawing, which shows, byway of exampleialensconstriicted in accorda-neewithmy"'invention,-"Fig. 1 is a I vertical sectional view taken centrally through a" vehicle headlight having my iimproved lens applied thereto; andfFig. 2 is a frontview of the lens shown 'in liig; 1.

In the "drawing," the numeral 2" designates 4 and a clamping ring or lens holder 5. These parts may be of any usual or desired construction.

My improved lens is shown within the clamping ring 5, and consists of a flat outer ring 6 and a series of concentric and successively projecting annular prisms 7 8, 9 and 10, the prism 10 merging into a central bulls-eye 11, the interior and exterior surfaces of which are curved outwardly. Each of the annular prisms 7, 8 and 9 has an exterior surface 12 which is substantially perpendicular to the central axis AB of the lens and has another exterior surface 13 which is inclined inwardly with respect to the axis A-B.

The prisms 7, 8 and 9 may be considered 19 229 seria'rm. mass.

as being 5 triangular in cross-section and oined to each other by means of plane rlngs 5 1ft, or these prisms may be considered as the outer portions of"1ntegral r1ngs, lncludmg both theprisms and the plane portions 14.

The interior-surface of the lens is formed by the 'sui'faces 15 which are perpendicular, "or substantiallyperpendicular, to the axis A B, and cylindrical "surfaces16 whichare substantially parallel to the axis AB. The msideofthe lens thus presents a series of concentric right-angledstepsterminating in the central bulls-eye 11.

All of the'inner surfaces of the lenswhich are transverse to the central axis *AB" are "lna-de translucent. These surfaces include the inner surface-of the ring 6,-thes ;i-r-faces 15 'of the annular'prisms,',and the inner surface of the bulls-eye 11. *All of theexterior surfaces of the'l'ens are preferablytranspar'ent,-as are also the-cylindrical inner surfaces 16.

One desirable way in" which 'the inner and baking thelens' to transform the'coat'ing into a' hard and integral portion of the l'ens which-will 'not"scale 01f. Other means may be employed formaking these surfaces transueen-t; such as sand'-lolasting,-grinding" or painting. I have found that Zinc-oxid,when applied to the" inn'er lens surfaces in the manner described, produces a milky white appearance which is both attractive=-and eflian ordinary headlight casing provided with an incandescent lamp 3, a parabolic reflector cient.

'The arrangement of prisms described above directs the light in a variety of directions, a few of which are indicated in broken lines on the drawing. Some of the light penetrates the translucent surfaces and is directed forwardly, as shown, for example, by the lines C. Other rays are refracted by the prisms in a lateral and rearward direction, as shown, for example, by the lines D and E, and serve to illuminate a considerable area at the side and rear of the lens.-

No attempt has been made to show on the drawing the numerous other and more complicated paths in which the light is reflected and refracted.- The general result is that when the lamp 8 is illuminated the lens presents the appearance. from the front of a background of low brilliancy on which appears a series of concentric silvery rings which are the outer edges of the projecting prisms 7, 8 and 9. The portion of each prism which presents this bright appearance is that portion between the outer edge of the prism and the projection of the adj acent angle of the prism. This bright por tion of the prism 7 is indicatedby the numeral 20 on Fig. 1, and consists of that portion of the prism between its outer edge and the line 21. Between the line 21, and the line 22 is a band of somewhat, less brilliancy, adjacent to which is a. dull transluto the side is sufiicient for illumination withp out being dazzling. I

The central bulls-eyemay be attractively ornamented by applying a monogram or the like in gold or colors beforethe translucent coating is applied.

When my invention is applied to lenses for use in'illumina'ting fixtures other than vehicle headlights, the same construction may be employed as that described above, with only such changes as are required to adapt the lens for use with the desired lighting fixtures. It will be und-ersood that the number and size of the prisms composingthe lens may be varied as desired and that, al though'the accompanying drawing shows one form in which I have constructed my invention with excellentresults, the proportions and arrangement of parts may be variously modified within the scope of the ap-- pended claims.

I I claim as my invention: v

1. A lens comprising a series of concen' tric annular prisms decreasing successively in diameter and each having two exterior surfaces intersecting at an acute angle, one

of said exterior surfaces being inclined with respect to the central axis of the lens, and the other exterior surface being substantially perpendicular to the central axis of the lens, translucent rings separating said annu- 'is substantially perpendicular and the other substantially parallel to the central axis of the lens, all of the inner surfaces of the lens that are perpendicular to the central axis of the lens being translucent.

3. A lens comprising a'seriesof concentric annular prisnrs decreasing successively in diameterand separated by translucent plane rings ext-ending perpendicular to the central axis of the lens, a translucent outer ring also extending perpendicular to the said axis, and a trans'lucent bulls-eye forming a continuation of the central prism, each of said prisms having exterior surfacesintersecting at an acute anglep'one .of said exterior surfaces being inclined with respect to the central axis of the lens, and the other exterior surface being substantially perpendicular to the central axis ofthe lens.

- 4. A lens comprising a series of concentric annular prisms decreasing successively in diameter and each having two exterior surfaces intersecting at an acute angle, one of said exterior surfaces. being substantially perpendicular tothe central axis of the lens, and translucent rings separating said annular prisms. s Y i v In: testimonyjwhereof' I the said JOHN DAHLsTRoM havev hereunto set my hand.

JOHN, DA LsrRoM. 

